Compressed natural gas vehicle safety system and method

ABSTRACT

A multiply-redundant system that prevents a driver from starting and/or moving a vehicle if a compressed natural gas fill system is not correctly and completely disconnected from the vehicle. One or more sensors in combination with one or more optional microswitches combine to lock-out the vehicle&#39;s ignition or otherwise prevent it from starting and/or moving. For different levels of safety, different combinations of sensors can be used with the lowest level having a single proximity sensor sensing the presence or absence of a high-pressure fill hose. The highest level of safety being achieved by having separate proximity sensors on the fuel fill hose fitting, the gas cap cover and a manual safety valve along with a redundant microswitch. An optional override that may be restricted as to the number of times it can be used can allow starting with a faulty sensor in order to allow maintenance.

This is a continuation of application Ser. No. 15/925,891 filed Mar. 20,2018 which was a continuation of application Ser. No. 15/257,030 filedSep. 6, 2016, now U.S. Pat. No. 9,919,663 issued Mar. 20, 2018 which wasa continuation of application Ser. No. 14/194,131 filed Feb. 28, 2014,now U.S. Pat. No. 9,434,329 issued Sep. 6, 2016 which was a continuationof application Ser. No. 13/463,022 filed May 3, 2012, now U.S. Pat. No.8,662,235 issued Mar. 4, 2014. Application Ser. No. 15/925,891, Ser. No.15/257,030, Ser. No. 14/194,131 and Ser. No. 13/463,022 are herebyincorporated by reference in their entireties.

BACKGROUND Field of the Invention

The present invention relates generally to the fields of vehicle safetyand compressed natural gas and more particularly to safety systemrelated to fueling vehicles powered by compressed natural gas.

Description of the Prior Art

Natural gas is becoming an abundant resource in the United States andseveral other countries. It is estimated that the natural gas reservesof the U.S. exceed the oil reserves of Saudi Arabia in terms of years ofenergy supply.

In order to utilize this resource effectively, and to replace crude oil,natural gas must be used in vehicles. Many fleet operators are switchingtheir vehicles to natural gas since, with minor modifications, internalcombustion engines run very well on natural gas.

Natural gas is typically supplied in two different forms: 1) as acompressed gas, and 2) as a liquefied gas. While more efficient in termsof the amount of gas that can be supplied in a single tank, liquefiedgas is very dangerous to handle and requires highly specializedequipment to fuel with it and actually use it. On the other hand,compressed natural gas is relatively easy to fuel with and to utilize.Compressed natural gas can be supplied in pressure bottles a pressuresbetween 3000 psi and 4000 psi. It is very well known in industry how tohandle and fill such bottles. A natural gas “gas station” can fill avehicle tank (pressure bottle) in just a few moments using filltechniques similar to high pressure air. A vehicle tank containing100-200 cu. feet of natural gas at a pressure of 3500 psi is typicallynot more dangerous than a typical automobile's gasoline tank. The tankcan be shielded from direct impact in an accident.

Many households and businesses in the U.S. have piped in natural gas forcooking and, in many cases, heating. Most Americans own at least one caror other vehicle, with many households owning several vehicles. Thiscombination immediately suggests the possibility of filling a naturalgas vehicle at home during the night for use the next day, or filling atthe location of a small business. Because even a large compressednatural gas tank will not last as long between refills as a typicalgasoline tank, it will become a very convenient to refill it during thenight. The vehicle owner can also use natural gas filling stations;however, these will probably be more convenient for extended trips. Mostpeople would prefer not to have to wait 5-10 minutes at a gas station tofill their vehicle. While exchangeable tanks are also possible, theserequire considerably more logistics and handling than a simple fixedonboard tank. Even with exchangeable tanks, the vehicle owner wouldstill probably have to wait considerably longer to get a refill at astation than they currently do with gasoline.

At the present time, at least one car manufacturer is supplying acompressed natural gas vehicle and a home compressor to fill it.National fire codes currently prevent large gas storage tanks in homesor compressors that fill at fast rates. Given present standards, thehome compressor will be directly attached to the vehicle via a highpressure hose, and the vehicle will take several hours to fill(depending on the size of the onboard tank). Again, this will be veryconveniently accomplished during the night. The same arrangement can beused at small businesses, especially those with fleets of vehicles.

However, with numerous individuals filling natural gas vehicles in theirgarages at night or at their business locations, the potential for avery serious type of accident increases dramatically—namely what iscalled a drive-off accident. This is where the driver tries to driveaway with the high pressure filling hose still attached to the vehicle.Such an accident in a home garage could be catastrophic if the fittingor valve on the vehicle is damaged, or if the compressor is pulled awayfrom the home natural gas source. In either case, a considerably amountof gas could escape into the garage causing a fire or explosion danger.Also, even a “soft” drive-away accident, one where the driver stoppedbefore breaking the hose or fitting could stress the fill hose andpossibly cause small, very hard to detect, gas leaks. Such small leakscould result in the garage being filled with gas by morning.

Natural gas contains mostly methane and is thus lighter than air.Natural gas leaking in a garage will fill the garage from top to bottom.An explosive mixture for natural gas and air is between around 5% (forpure methane) and around 15-20%. Many garages contain furnaces and waterheaters having open flames. As natural gas fills a garage, it can beeasily ignited by a furnace or a water heater on a raised pedestal (firecodes require open flame devices in garages to mounted on pedestals toavoid gasoline vapor that might collect along the floor from a cargasoline leak). This is an ideal situation for a garage explosion. Henceanything that has the possibility of causing the release of natural gasor of causing a gas leak becomes a large danger. A drive-away accidentis such an event.

Some techniques have been reported in the art to prevent a gasolinevehicle from starting at a gasoline station if the fill nozzle is stillin the gas tank inlet. Among these are U.S. Published Application No.2002/0162601 and U.S. Pat. No. 5,720,327. Other techniques have beeninvented to prevent pumping gasoline or other fuel if the fill hose isnot in the fill inlet. Among these are U.S. Published Application No.2008/0290152 and U.S. Pat. No. 4,227,497.

While these prior art techniques are useful for gasoline, they do notsolve the problems associated with home or business filling a vehiclewith high pressure compressed natural gas. In particular, a compressednatural gas tank is filled to a very high pressure (between 3000 and4000 psi). A leak or disconnect of a fitting or valve on such a pressurevessel can cause a tremendous pressure explosion that can act like abomb (this can happen with any compressed gas including air). Also, avery small leak at high pressure can cause a large quality of gas toescape. For example, an exploding tank can send metal fragments in alldirections with enough force to penetrate the house and the driver'scompartment of the vehicle. This can happen before there is any fire.After that, the tiniest spark could ignite the now explosive and highlyflammable gas cloud reducing the house or business to rubble. Even aquick-disconnect hose does not typically solve the problem since thedriver may attempt to drive away very quickly still damaging thefittings, tank, hose, compressor and/or natural gas supply.

It would be very advantageous to have doubly or triply redundant systemand method that prevents the driver from ever starting the vehicle whenthe filling hose is attached and a safety valve is not in the correctposition.

SUMMARY OF THE INVENTION

The present invention relates to a multiply-redundant system and methodfor preventing a driver from starting or moving a compressed natural gasvehicle if the high pressure gas fill system is not correctly andcompletely disconnected from the vehicle.

In one embodiment of the invention, multiple electrical proximitysensors, or other sensors, in combination with one or more optionalmechanical microswitches combine to lock-out the vehicle's ignition orotherwise disable the vehicle. For different levels of safety, differentcombinations of sensors can be used, with the lowest level having asingle sensor sensing the presence or absence of a fuel supply fitting.The highest level of safety according to the invention is to haveseparate sensors, such as proximity sensors, on the fuel fill hosefitting, the gas cap cover and a manual safety or isolation valve alongwith a redundant microswitch on at least one of the components. Theignition, transmission or other function can be locked out by anelectrical or mechanical lockout provided to the vehicle's computer bythe manufacturer, or by a simple series electrical circuit in theignition string. The safest system could use both techniques.

In addition, the vehicle's computer, or another simple electricalcircuit, could provide a visual and/or audio indication that one or moreof the sensors was indicating an attached fuel hose. The alarm could beactivated the instant the driver inserts a key into the ignition. Underthe present invention, it is understood that there is a possibility thatone of the sensors might fail in a state that indicates the fuel hose isconnected when, in reality, the system is entirely safe. In this veryspecial case, the present invention provides a technique for the driver,on a limited-time basis, to override the sensors and start the engine ormove the vehicle using a supplied override. Having this feature allowsthe driver to drive to a mechanic to have the problem fixed. Thisfeature could be automatically disabled by an abuse preventer after apredetermined number of uses (such as three times) to keep a driver witha bad sensor from delaying getting it fixed. Finally, an optionalbreak-away fitting can also be provided in addition to the otherfeatures of the invention for a final level of protection.

DESCRIPTION OF THE FIGURES

Attention is now directed to several drawings the illustrate features ofthe present invention:

FIG. 1A shows a block diagram of an embodiment of a high-safety lock-outsystem according to the present invention.

FIG. 1B shows a logic circuit that can combine sensors inputs.

FIG. 2 shows a detail drawing of a fill fixture with a proximity sensor.

FIG. 3 shows the system of FIG. 2 with the high pressure fill hoseremoved.

FIG. 4 shows a system similar to that of FIGS. 2-3 with an additionalgas cap sensor.

FIG. 5 shows a panel-type filling system with an isolation valve andthree proximity sensors.

FIG. 6 shows the system of FIG. 5 with an additional mechanicalmicroswitch.

Several drawings and illustrations have been presented to aid inunderstanding the present invention. The scope of the present inventionis not limited to what is shown in the figures.

DETAILED DESCRIPTION OF THE INVENTION

The present invention relates to a system and method that provides alockout out to a vehicle's ignition, transmission or other means ofmoving the vehicle when a high pressure compressed natural gas fuel hoseis attached to the vehicle an/or the fill cap is open. FIG. 1A shows ablock diagram of an embodiment of such a system. A compressed gas fuelfitting 2 accepts a high pressure filling hose 21 that allows fillingthrough an isolation valve 22. The isolation valve 22 can be manuallyopened, or it can be opened mechanically when a panel lid or “gas cap”is opened. A sensor 4, which can be an electrical proximity sensor,senses the presence of the fitting part of the high pressure fillinghose 21. An optional second sensor 8 senses that the panel or gas cap isopen. An optional third sensor 14 can sense the position of an isolationvalve 22 (on vehicles that have such a valve). All of the sensors can bemagnetic, optical or ultra-sonic proximity sensors, or any othersensors, and use any method of sensing proximity or that a particularmechanical part is or is not in a particular position. One or moreoptional mechanical microswitches 23 can provide a backup to one or moreof the sensors.

A further logic circuit 24 or other lockout which can be a separateunit, or part of the vehicle's processor, can combine the inputs fromall the sensors 4, 8, 14, and the optional microswitch 23 to produce asafe signal 25 that will allow the vehicle ignition to start the car, orotherwise allow the vehicle to move. FIG. 1B shows a schematicrepresentation of this circuit 24. Here, each sensor's signal isamplified and conditioned and fed into an AND logic circuit 26. If anyof the sensors is in an unsafe condition, the AND circuit 26 will notproduce a “safe” signal. The particular circuit of FIG. 1B assumes thata proximity sensor has a logic high when there is proximity, and thatthe microswitch is high when the lid is closed. Any other logic levelsor configurations can be used. In particular, a program in amicrocontroller or other processor could also make the determination. Asis well understood in the art, an OR circuit could also be effectivelyused instead of an AND circuit. Any circuit or program that combinessensor inputs to make a “safe” determination is within the scope of thepresent invention.

FIG. 1B also shows an override 27 that can be used to force a “safe”condition when one of the sensors is in an unsafe state. This circuit isoptional but, when provided, allows the driver to drive to a mechanicwith a failing sensor. A counter 28 or other abuse preventer preventsthe override from being used more than a predetermined number timesbefore repairing the sensor (for example three times). The counter 28can be optionally reset whenever the sensor logic produces a safesignal. In the present example, the driver can enter a special PIN code29 to activate the override and override the sensors. While providingthis circuit lowers the overall safety threshold of the system slightly,the act of performing the override can be made difficult enough that adriver will not routinely use it to avoid having to fix a faulty sensor.Optionally, the override could be restricted to use only by a certifiedmechanic. In this case, the driver would not be allowed to operate it.While a simple override switch can be used, for additional safety, a PINor barcode or any other unique identification 29 might be required. If aPIN is used, a PIN entry method can be used such as a keypad or a cardswipe. If a barcode is used, a small barcode reader can be supplied.

FIG. 2 shows a male tank adapter 2 on the vehicle with a coupled(usually spring coupled) female filling locking coupler 3 and highpressure feed hose 1. The feed hose 1 typically originates at acompressor or storage tank. A proximity sensor 4 with electricalconnections 5 senses the presence of the feed hose (unsafe condition).The female locking coupler 3 typically has a connect/disconnect fittingthat clamps the tank adapter 2 and makes a high pressure, leak-proofconnection. It should be noted that the female filling locking coupler 3could be a quick-release, break-away fitting. This would add a finalmechanical precaution to the system where the hose would manually breakfree in the case that somehow the rest of the system failed.

FIG. 3 shows the same setup but with the feed hose 1 and the femalelocking coupler 3 uncoupled and withdrawn (safe position) from the malefilling adapter 2.

FIG. 4 shows a fill cavity 6 and fill access lid 7 that swings open onhinges. A second proximity sensor 8 has a second electrical feed 9. Thissensor 8 can be used in embodiments of the invention either alone or inconjunction with the feed hose sensor 4. An optional microswitch 20 isalso shown.

Any type of sensor can be used with the present invention. A preferredsensor is a magnetic or optical proximity sensor; however, other sensortypes can be used such as ultra-sonic sensors and others.

FIG. 5 shows a different arrangement of the fueling system. This type ofsystem is more commonly found on trucks and larger vehicles. A panel 13opens and closes to allow access to a tank adapter 12. An isolationvalve 10 can be manually operated or can operate in conjunction with alever 16 on the panel 13. A third proximity sensor 14 with electricalfeed 15 can be used to sense whether the panel is open or closed (andhence, if the lever 16 is used with the valve 10, whether the valve isopen or closed). The valve 10 isolates the tank adapter 12 from the tankwhen the panel is closed.

FIG. 6 shows the same embodiment as FIG. 5 except that an optionalmicroswitch 23 has been added to the panel 13. This is a simplemechanical backup that does not rely on proximity sensors. It should benoted that any of the proximity sensors shown in the various embodimentsof the present invention may be replaced by microswitches or othermechanical devices, or each proximity sensor may be optionally backed upwith an additional microswitch. In addition, FIG. 6 shows an optionaladditional microswitch 21 on the isolation valve 10.

It should be noted that an optional natural gas leak sensor can also beincluded with the system of the present invention to provide an additionsource of safety. Such a sensor could keep the vehicle in a disabledstate if an unreasonable concentration of free natural gas is sensed.Such a sensor could also sound an alarm on the vehicle or on thecompressor. It is also possible that any of the above-mentioned sensorsor circuits can communicate with the lockout or other logic wirelesslysuch as by radio or light. Finally, it should be noted that a processorwith memory and a stored program can perform the logic function of thelockout, override and/or abuse preventer. This can also be any digitalor analog logic circuit or simply relays. In addition, an internet ornetwork interface can be provided to remotely report or log the statusof the system. This feature can be useful for fleet operators to tracksafety, for example, the number of attempts to drive off under a lockoutcondition or the number of overrides.

The present invention provides a multiply-redundant system to enhancethe safety of home or business fueling of compressed natural gasvehicles. It can also be used on vehicles using propane or any othercompressed gas fuel. A system of one or more sensors determines if thefueling system is in a safe state. This can be a state with the highpressure fill hose removed, the fueling compartment access lid closed,and any isolation valve in the correct position. A lockout preventseither the vehicle from starting or otherwise makes it impossible tomove the vehicle when the system is not in a safe state. In order that adriver can get a faulty sensor repaired, an override can be providedthat allows the safety sensors to be overridden and the vehicle moved.This override can be equipped with an abuse preventer that only allowsthe override to be used for a predetermined number of times before theoverride itself is disabled. This prevents a driver from putting offgetting a faulty sensor repaired. An audio and/or visual indicator cansound or display when the driver inserts the key into the ignition in anunsafe state, or alternatively, when the driver turns the key to start.

In the present invention, a lockout is any method, means or technique toprevent a vehicle from moving including a circuit or module that candisable the ignition or transmission or disable the vehicle in any otherway. An override is a any method, means or technique to allow thevehicle to move in spite of the lockout - any way of overriding thelockout. An abuse preventer is any method, means or technique to preventabuse of the override by limiting the number of times (especiallysuccessive times) it can be used.

Several descriptions and illustrations have been presented to aid inunderstanding the features of the present invention. One with skill inthe art will realize that numerous changes and variations may be madewithout departing from the spirit of the invention. Each of thesechanges and variations is within the scope of the present invention.

I claim:
 1. A vehicle safety system for disabling a vehicle powered by acompressed fuel gas while fueling, the vehicle having an ignition andtransmission, the vehicle safety system comprising: a proximity sensoradapted to sense presence of a gas fill hose in proximity to a tank filladapter coupled to a pressurized gas source, said first sensor incommunication with a logic circuit; the logic circuit adapted to producea safe electrical signal indicating a safe condition when said fill hoseis not in proximity to said tank fill adapter; a lockout circuit adaptedto disable said vehicle when said safe electrical signal is absent; amechanical lockout constructed to lock out the ignition or thetransmission while the vehicle is fueling; a gas sensor configured tocause an alarm when said gas sensor senses a predetermined level of saidfuel gas.
 2. The vehicle safety system of claim 1 further comprising abreak-away fitting on said gas fill hose adapted to stop gas flow ifsaid vehicle drives away with the gas fill hose attached.
 3. The safetysystem of claim 1, wherein the gas sensor is also coupled to the logiccircuit preventing production of said safe electrical signal when thesensor senses a predetermined level of the fuel gas.
 4. The vehiclesafety system of claim 1 further comprising an override that overridessaid logic circuit and produces said safe electrical signal whenactivated.
 5. The vehicle safety system of claim 4 wherein said overrideis adapted to be used only a predetermined number of successive times 7.The vehicle safety system of claim 5 further comprising a countercircuit adapted to count successive uses of said override, and whereinsaid counter circuit is reset when said logic circuit produces said safeelectrical signal.
 8. The vehicle safety system of claim 1 wherein saidproximity sensor is magnetic, optical or ultra-sonic.
 9. The vehiclesafety system of claim 1 wherein said compressed fuel gas is propane.10. The vehicle safety system of claim 1 wherein said compressed fuelgas is natural gas.
 11. The vehicle safety system of claim 1, whereinfueling is monitored from a remote station via a network.
 12. A vehiclesafety system for disabling a vehicle powered by a compressed fuel gaswhile fueling, the vehicle having an ignition and transmission, thevehicle safety system comprising: a proximity sensor adapted to sensepresence of a gas fill hose in proximity to a tank fill adapter coupledto a pressurized gas source, said first sensor in communication with alogic circuit; the logic circuit adapted to produce a safe electricalsignal indicating a safe condition when said fill hose is not inproximity to said tank fill adapter; a lockout circuit adapted todisable said vehicle when said safe electrical signal is absent; amechanical lockout constructed to lock out the ignition or thetransmission while the vehicle is fueling.
 13. The vehicle safety systemof claim 12 further comprising a gas sensor configured to cause an alarmwhen said gas sensor senses a predetermined level of said fuel gas. 14.The vehicle safety system of claim 12 wherein said compressed fuel gasis propane.
 15. The vehicle safety system of claim 12 wherein saidcompressed fuel gas is natural gas.